Implantable leads with a conductor coil having two or more sections

ABSTRACT

Various coiled conductors having two or more sections and methods and devices for constructing such conductors are disclosed. The various embodiments of coiled conductors and related methods include two or more sections that can have different mechanical, structural, and/or electrical characteristics.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 12/979,911,filed Dec. 28, 2010, which claims priority under 35 U.S.C. §119 to U.S.Provisional Application No. 61/291,151, filed on Dec. 30, 2009, entitled“Implantable Leads with a Conductor Coil Having Two or More Sections,”which is hereby incorporated herein by reference in its entirety for allpurposes.

TECHNICAL FIELD

The various embodiments disclosed herein relate to body implantablemedical devices for sensing electrical impulses and/or deliveringelectrical stimulation in a body, and more particularly, to methods anddevices relating to a coiled conductor having at least two sections.

BACKGROUND

Various types of medical electrical leads for use in cardiac rhythmmanagement systems are known. Such leads are typically extendedintravascularly to an implantation location within or on a patient'sheart, and thereafter coupled to a pulse generator or other implantabledevice for sensing cardiac electrical activity, delivering therapeuticstimuli, and the like. The leads are desirably highly flexible toaccommodate natural patient movement, yet also constructed to haveminimized profiles. At the same time, the leads are exposed to variousexternal forces imposed, for example, by the human muscular and skeletalsystem, the pulse generator, other leads, and surgical instruments usedduring implantation and explanation procedures. There is a continuingneed for improved lead designs.

SUMMARY

Discussed herein are various coiled conductors for implantable medicalelectrical leads, including coiled conductors having two or moresegments, as well as medical electrical leads including such conductors.

In Example 1, a medical lead comprises a lead body, at least one lumendisposed within the lead body, and a coiled conductor disposed withinthe lumen. The coiled conductor comprises a first coiled segment, asecond coiled segment, and a junction member coupled to an end of thefirst and second coiled segments. The first coiled segment comprises afirst number of filars and a first pitch and the second coiled segmentcomprises a second number of filars and a second pitch.

Example 2 relates to the medical lead according to Example 1, whereinthe first coiled segment further comprises a first outer diameter and afirst inner diameter and the second coiled segment further comprises asecond outer diameter and a second inner diameter.

Example 3 relates to the medical lead according to either Example 1 or2, wherein the first outer diameter is greater than the second outerdiameter and the first inner diameter is greater than the second innerdiameter.

Example 4 relates to the medical lead according to any of Examples 1-3,wherein the first number of filars is less than the second number offilars.

Example 5 relates to a medical lead according to any of Examples 1-4,wherein the first coiled segment comprises coated filars and the secondcoiled segment comprises uncoated filars.

Example 6 relates to a medical lead according to any of Examples 1-5,wherein the first coiled segment is a first coiled conductor and thesecond coiled segment is a second coiled conductor.

Example 7 relates to a medical lead according to any of Examples 1-6,wherein the junction member is a weld zone.

Example 8 relates to a medical lead according to any of Examples 1-6,wherein the junction member is a junction ring.

Example 9 relates to a medical lead according to Example 8, wherein thejunction ring comprises a male coupling component configured to bedisposed within a lumen at the end of the first coiled segment and afemale coupling component comprising a lumen configured to receive theend of the second coiled segment.

Example 10 relates to a medical lead according to Example 8, wherein thejunction ring comprises a first female coupling component comprising alumen configured to receive the end of the first coiled segment and asecond female coupling component comprising a lumen configured toreceive the end of the second coiled segment.

Example 11 relates to a medical lead according to Example 8, wherein thejunction ring comprises a first male coupling component configured to bedisposed within a lumen at the end of the first coiled segment and asecond male coupling component configured to be disposed within a lumenat the end of the second coiled segment.

According to Example 12, a medical lead comprises a lead body, at leastone lumen disposed within the lead body, and a coil conductor disposedwithin the lumen. The coil conductor comprises a proximal coiledsegment, a distal coiled segment, and a junction member coupled to thedistal end of the proximal coiled segment and the proximal end of thedistal coiled segment. The proximal segment comprises a first number ofcoated filars, a first pitch, and a first outer diameter. The distalsegment comprises a second number of uncoated filars, a second pitch,and a second outer diameter that is less than the first outer diameter.

Example 13 relates to a medical lead according to Example 12, whereinthe junction member is a weld zone.

Example 14 relates to a medical lead according to Example 12, whereinthe junction member is a junction ring comprising a male couplingcomponent configured to be disposed within a lumen at the distal end ofthe proximal coiled segment and a female coupling component comprising alumen configured to receive the proximal end of the distal coiledsegment.

According to Example 15, a method of constructing a coil conductorhaving at least a first segment and a second segment comprises winding afirst number of at least one filars into a coiled configuration over afirst section of a mandrel to form the first segment and winding asecond number of at least one filars beginning at the transition pointinto a coiled configuration over a second section of the mandrel to formthe second segment. The winding to form the first segment ends at atransition point. The first section has a first outer diameter and thesecond section has a second outer diameter. The first segment includesthe first number of at least one filars, a first pitch, and a firstinner diameter. The second segment has the second number of at least onefilars, a second pitch, and a second inner diameter. At least one of thefirst number of filars, the first pitch, the first inner diameter, andthe first outer diameter is different from at least one of the secondnumber of filars, the second pitch, the second inner diameter, and thesecond outer diameter.

Example 16 relates to a medical lead according to Example 15, whereinthe at least one filar is a coated filar and wherein the method furthercomprises removing the coating while winding the at least one filar toform either the first segment or the second segment, whereby one of thefirst and second segment is uncoated.

Example 17 relates to a medical lead according to Example 15 or 16, andfurther comprises removing one of the first number of filars at thetransition point before winding the second number of filars, whereby thesecond number of filars is less than the first number of filars.

Example 18 relates to a medical lead according to Example 15 or 16, andfurther comprises adding a filar at the transition point before windingthe second number of filars, whereby the second number of filars isgreater than the first number of filars.

Example 19 relates to a medical lead according to any of Examples 15-18,wherein the second outer diameter of the mandrel is smaller than thefirst outer diameter of the mandrel.

Example 20 relates to a medical lead according to any of Examples 15-19and further comprises winding a third number of the at least one filarsbeginning at a second transition point into a coiled configuration overa third section of the mandrel to form a third segment, wherein thethird section comprises a third outer diameter and the third segmentcomprises the third number of at least one filars, a third pitch, and athird inner diameter, wherein at least one of the second number offilars, the second pitch, the second inner diameter, and the secondouter diameter is different from at least one of the third number offilars, the third pitch, the third inner diameter, and the third outerdiameter.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic drawing of a cardiac rhythm management systemincluding a pulse generator coupled to a pair of medical electricalleads deployed in a patient's heart, according to one embodiment.

FIG. 1B is a perspective view of one of the leads shown in FIG. 1,according to one embodiment.

FIG. 1C is a schematic cross-section drawing of a portion of a lead,according to one embodiment.

FIG. 2A is a schematic cross-section drawing of a coiled conductor witha junction ring, according to one embodiment.

FIG. 2B is a perspective view of the coiled conductor of FIG. 2A,according to one embodiment.

FIG. 3A is a side view of an attachment tube, according to oneembodiment.

FIG. 3B is a cross-sectional view of the attachment tube of FIG. 3A,according to one embodiment.

FIG. 4A is a schematic cross-section drawing of a coiled conductor witha junction ring, according to another embodiment.

FIG. 4B is a perspective view of the junction ring of FIG. 4A, accordingto one embodiment.

FIG. 5A is a schematic cross-section drawing of a coiled conductor witha junction ring, according to yet another embodiment.

FIG. 5B is a perspective view of the junction ring of FIG. 5A, accordingto one embodiment.

FIG. 6 is a schematic view of a portion of a coiled conductor with aweld zone, according to one embodiment.

FIG. 7A is a schematic view of one method of creating a coiled conductorwith a weld zone, according to one embodiment.

FIG. 7B is a schematic view of another method of creating a coiledconductor having a weld zone, according to another embodiment.

FIG. 7C is a schematic view of still another method of creating a coiledconductor having a weld zone, according to still another embodiment.

FIG. 8 is a side view of a portion of a coiled conductor having twosegments, according to one embodiment.

FIG. 9 is a perspective view of a lead, according to one embodiment.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

The various embodiments disclosed herein relate to a coiled wireconductor for use in a medical electrical lead and related methods anddevices for manufacturing the conductor. The leads according to thevarious embodiments of the present invention are suitable for sensingintrinsic electrical activity and/or applying therapeutic electricalstimuli to a patient. Exemplary applications include, withoutlimitation, cardiac rhythm management (CRM) systems and neurostimulationsystems. For example, in exemplary CRM systems utilizing pacemakers,implantable cardiac defibrillators, and/or cardiac resynchronizationtherapy (CRT) devices, the medical electrical leads according toembodiments of the invention can be endocardial leads configured to bepartially implanted within one or more chambers of the heart so as tosense electrical activity of the heart and apply a therapeuticelectrical stimulus to the cardiac tissue within the heart.Additionally, the leads formed according to embodiments of the presentinvention may be particularly suitable for placement in a coronary veinadjacent to the left side of the heart so as to facilitatebi-ventricular pacing in a CRT or CRT-D system. Still additionally,leads formed according to embodiments of the present invention may beconfigured to be secured to an exterior surface of the heart (i.e., asepicardial leads). FIG. 1A is a schematic drawing of a cardiac rhythmmanagement system 10 including a pulse generator 12 coupled to a pair ofmedical electrical leads 14, 16 deployed in a patient's heart 18, whichincludes a right atrium 20 and a right ventricle 22, a left atrium 24and a left ventricle 26, a coronary sinus ostium 28 in the right atrium20, a coronary sinus 30, and various coronary veins including anexemplary branch vessel 32 off of the coronary sinus 30.

According to one embodiment, as shown in FIG. 1A, lead 14 includes aproximal portion 42 and a distal portion 36, which as shown is guidedthrough the right atrium 20, the coronary sinus ostium 28 and thecoronary sinus 30, and into the branch vessel 32 of the coronary sinus30. The distal portion 36 further includes a distal end 38 and anelectrode 40 both positioned within the branch vessel 32. Theillustrated position of the lead 14 may be used for delivering a pacingand/or defibrillation stimulus to the left side of the heart 18.Additionally, it will be appreciated that the lead 14 may also bepartially deployed in other regions of the coronary venous system, suchas in the great cardiac vein or other branch vessels for providingtherapy to the left side or right side of the heart 18.

In the illustrated embodiment, the electrode 40 is a relatively small,low voltage electrode configured for sensing intrinsic cardiacelectrical rhythms and/or delivering relatively low voltage pacingstimuli to the left ventricle 26 from within the branch coronary vein32. In various embodiments, the lead 14 can include additionalpace/sense electrodes for multi-polar pacing and/or for providingselective pacing site locations.

As further shown in FIG. 1A, in the illustrated embodiment, the lead 16includes a proximal portion 34 and a distal portion 44 implanted in theright ventricle 22. In other embodiments, the CRM system 10 may includestill additional leads, e.g., a lead implanted in the right atrium 20.The distal portion 44 further includes a flexible, high voltageelectrode 46, a relatively low-voltage ring electrode 48, and a lowvoltage tip electrode 50 all implanted in the right ventricle 22 in theillustrated embodiment. As will be appreciated, the high voltageelectrode 46 has a relatively large surface area compared to the ringelectrode 48 and the tip electrode 50, and is thus configured fordelivering relatively high voltage electrical stimulus to the cardiactissue for defibrillation/cardioversion therapy, while the ring and tipelectrodes 48, 50 are configured as relatively low voltage pace/senseelectrodes. The electrodes 48, 50 provide the lead 16 with bi-polarpace/sense capabilities.

In various embodiments, the lead 16 includes additionaldefibrillation/cardioversion and/or additional pace/sense electrodespositioned along the lead 16 so as to provide multi-polardefibrillation/cardioversion capabilities. In one exemplary embodiment,the lead 16 includes a proximal high voltage electrode in addition tothe electrode 46 positioned along the lead 16 such that it is located inthe right atrium 20 (and/or superior vena cava) when implanted. As willbe appreciated, additional electrode configurations can be utilized withthe lead 16. In short, any electrode configuration can be employed inthe lead 16 without departing from the intended scope of the presentinvention.

The pulse generator 12 is typically implanted subcutaneously within animplantation location or pocket in the patient's chest or abdomen. Thepulse generator 12 may be any implantable medical device known in theart or later developed, for delivering an electrical therapeuticstimulus to the patient. In various embodiments, the pulse generator 12is a pacemaker, an implantable cardioverter defibrillator (ICD), acardiac resynchronization (CRT) device configured for bi-ventricularpacing, and/or includes combinations of pacing, CRT, and defibrillationcapabilities.

FIG. 1B is a perspective view of the lead 14 shown in FIG. 1A. Asdiscussed above, the lead 14 is adapted to deliver electrical pulses tostimulate a heart and/or for receiving electrical pulses to monitor theheart. The lead 14 includes an elongated polymeric lead body 56, whichmay be formed from any polymeric material such as polyurethane,polyamide, polycarbonate, silicone rubber, or any other suitablepolymer.

In addition, the lead 14 can have one electrode 40 as shown in FIG. 1A,or the lead 14 may have more than one electrode as shown in FIG. 1B, inwhich the lead 14 has three electrodes 40, 52, 54 along its distalsection 36.

As further shown in FIG. 1B, the lead 14 further includes a connector 58operatively associated with the proximal end of the lead body 56. Theconnector 58 is configured to mechanically and electrically couple thelead 14 to the pulse generator 12 as shown in FIG. 1A, and may be of anystandard type, size or configuration. The connector 58 has a terminalpin 60 extending proximally from the connector 58. As will beappreciated, the connector 58 is electrically and mechanically connectedto the electrodes 40, 52, 54 by way of one or more conductors (notshown) that are disposed within an elongate tubular member 62 within thelead body 56 (as best shown in FIG. 1C).

In various embodiments, the elongate tubular member 62 depicted in crosssection in FIG. 1C defines multiple lumens (and is also referred toherein as a “multilumen tube”). In some implementations, the multilumentube 62 forms a central or inner portion of the lead body 56 and extendsfrom a proximal portion to a distal portion of the body 56. As shown, insome embodiments the multilumen tube 62 has four lumens 64, 66, 68, 70.In other embodiments, the multilumen tube 62 has a single lumen, two ormore lumens, three or more lumens, four or more lumens, or any othersuitable number of lumens. Further, in some embodiments one or more ofthe lumens are offset from the longitudinal axis of the multilumen tube62. For example, the first lumen 64 has a longitudinal axis that isnon-coaxial with respect to the longitudinal axis of the multilumen tube62.

As mentioned above, in some embodiments the lumens 64, 66, 68, 70provide a passageway through which conductors can pass and electricallyconnect one or more of electrodes 40, 52, 54 to the connector 58. Theconductors utilized may take on any configuration providing thenecessary functionality. For example, as will be appreciated, theconductor coupling the electrode 40 to the connector 58 (and thus, tothe pulse generator 12) may be a coiled conductor defining an internallumen for receiving a stylet or guidewire for lead delivery. As bestshown as an example in FIG. 1C, conductor 72 disposed in lumen 70 is anexample of a coiled conductor 72 defining an internal lumen 74 withinthe conductor 72. Conversely, in various embodiments, any of theconductors to any of the electrodes 40, 52, 54 may be multi-strand cableconductors.

FIGS. 2A and 2B depict a coiled conductor 80 according to oneembodiment. The conductor 80 has a proximal coil 82 and a distal coil 84that are coupled via a joint member 94. In the embodiment depicted inFIGS. 2A and 2B, the joint member 94 is a joint ring 94.

“Joint ring” is intended for purposes of this application to mean anycoupling component, structure, or device that is configured tomechanically and electrically couple two coiled conductors or coiledconductor segments in series. It is understood that any coiled conductorembodiment disclosed herein has at least two segments or sections,wherein “segment” and “section” are intended to be used interchangeablyfor purposes of this application. In some implementations, each of thesections or segments is a separate conductor coil. In alternativeembodiments, the sections or segments are part of the same coil.

In the embodiment shown in FIGS. 2A and 2B, the joint ring 94 has a malemember 96 which is positioned within the lumen of the conductor 82. Theouter surface 98 of the male member 96 is in contact with the filars 86at the distal end of the coiled conductor 82, thereby resulting in amechanical and electrical connection.

According to one implementation, at least one of the filars 86positioned on the male member 96 is welded or soldered or otherwiseattached to the member 96, thereby attaching the conductor 82 to thejoint ring 94. Alternatively, the filars 86 are attached to the malemember 96 by positioning an attachment tube 110 (as shown in FIGS. 3Aand 3B) over the filars 86 and the male member 96, thereby resulting inthe filars 86 being disposed between the male member 96 and theattachment tube 110. The tube has a body 112 and an inner lumen 114 andin this embodiment is sized to be disposed over the male member 96 andalso over the filars 86 that are positioned over the male member 96. Inone embodiment, once the tube 110 is in position over the male member 96and filars 86, the tube 110 is crimped or otherwise tightened againstthe filars 86 and member 96, thereby attaching the filars 86 to themember 96. In a further alternative, any form of mechanical attachmentcan be used to attach the conductor 82 to the ring 94.

The ring 94 also has a female member 100 defining a lumen 102 that hasan inner surface 104. In the embodiment of FIGS. 2A and 2B, the proximalend of the coiled conductor 84 is positioned in the lumen 102, resultingin the individual filars 92 at the proximal end of the coiled conductor84 being in contact with the inner surface 104 of the lumen 102, therebyresulting in a mechanical and electrical connection between the coiledconductor 84 and the joint ring 94.

In accordance with some implementations, the at least one of the filars92 positioned inside the lumen 102 is welded to the female member 100,thereby attaching the conductor 84 to the ring 94. In one exemplaryembodiment, the welding can be accomplished using the aperture 106 inthe outer wall of the female member 100. Alternatively, the filars 92are attached to the female member 100 by inserting an attachment tubeinto the lumen 102 formed by the female member 100 and the filars 92.According to one embodiment, the attachment tube 110 depicted in FIGS.3A and 3B can be one example of the attachment tube used with the femalemember 100. In this embodiment, the attachment tube 110 is sized to fitwithin the lumen 102 and also within the lumen formed by the filars 92disposed within the lumen 102, thereby resulting in the filars 92 beingdisposed between the female member 100 and the attachment tube 110. Inone embodiment, once the tube 110 is in position in the lumen 102, thefemale member 100 is crimped or otherwise tightened against the filars86 and tube 110, thereby attaching the filars 86 inside the lumen 102 ofthe female member 100. In a further alternative, any form of mechanicalattachment can be used to attach the conductor 84 to the ring 94.

In this embodiment, the male member 96 of the ring 94 defines a lumen108 that is in communication with the lumen 102 of the female member100, resulting in a ring 94 having a lumen that extends through theentire ring 94. In addition, as best shown in FIG. 2A, in certainimplementations of the ring 94, the inner diameter of the lumen 102 isgreater than the inner diameter of the lumen 108, thereby allowingadditional space in the lumen 102 for the filars 92 of the coil 84. Infact, in certain embodiments such as that depicted in FIG. 2A, thedifference in the diameters of the two lumens 102 and 108 issubstantially equal to the outer diameter of the filars 92 of the coil84, thereby allowing for the positioning of the filars 92 in the lumen102 without impacting the resulting inner diameter through the lumens102, 108, which remains substantially the same. As such, this lumen 102,108 allows for use of the joint ring 94 without disrupting the lumendefined through the entire length of the coupled coils 82, 84 or coilsegments 82, 84. In other words, the coupled coils 82, 84 with the ring94 still have a lumen through which any guidewire or stylet or othersimilar device can be inserted without any type of physical blockage orimpediment.

According to one embodiment, the ring 94 also has an additional featurethat allows for easy insertion of a stylet or other similar componentinto and through the lumen 108 in the ring 94. That is, the ring 94 hasa lip 110 defined at the opening of the lumen 108 that can guide anyinserted elongated device being inserted through coil 82 and into coil84 through the guide ring 94 without impeding the progress of thedevice.

While the embodiment of the ring 94 depicted in FIGS. 2A and 2B show thering 94 disposed such that the male member 96 is disposed to receive theproximal coil 82 and the female member 100 is disposed to receive thedistal coil 84, it is understood that the ring 94 can also be configuredsuch that the male member 96 receives the distal coil and the femalemember 100 receives the proximal coil. The depicted configuration inFIGS. 2A and 2B is exemplary and is not intended to be limiting withrespect to whether the male member 96 or female member 100 is positionedtoward the proximal coil or the distal coil.

In alternative embodiments, the joint ring can have two male members ortwo female members, depending on the design requirements of theparticular coil conductor or lead. For example, FIGS. 4A and 4B depict aconductor coil 120 having a joint ring 122 with two female members 132,136. The end of the first coiled conductor 124 is disposed within thelumen 134 of the first female member 132, and the end of the secondcoiled conductor 126 is disposed within the lumen 138 of the secondfemale member 136.

Similarly to the ring 94 in FIGS. 2A and 2B, the inner diameters of thelumens 134, 138 in various embodiments of the ring 122 can be configuredto provide for a substantially uniform inner diameter across both lumens134, 138 regardless of any difference between the outer diameters of thefilars 128, 130 of the two coils 124, 126. In other words, the innerdiameters of the two lumens 134, 138 can vary depending on the thicknessof the filars of the coils 124, 126 that the ring 122 is intended tocouple to ensure that the inner diameter of the lumens 134, 138 remainssubstantially uniform, thereby allowing for easy insertion of a styletor other similar device through the coil 120.

In accordance with one embodiment, the ring 122 has an inner shoulder144 disposed between the two lumens 134, 138. The shoulder 144 can serveto separate the first lumen 134 from the second lumen 138 and defines alumen 146 that is substantially equal to the inner diameters of thelumens 134, 138 when the coils 124, 126 are positioned therein. In otherwords, the lumen 146 must have an inner diameter at least as large asthe inner diameters of the lumens 134, 138 when those lumens contain thecoils 124, 126 in order to ensure that any stylet or other such devicecan be inserted through the ring 122. In addition, according to certainembodiments, the shoulder 144 can help to position the coils 124, 126 toensure that the appropriate amount of each coil 124, 126 is positionedin each lumen 134, 138 to achieve an appropriate mechanical and/orelectrical connection with the ring 94.

According to one implementation, the ring 122 has two slots 140, 142disposed in the outer walls of the two female members 132, 136. Each ofthe slots 140, 142 are provided to simplify the welding of the filars128, 130 of the two coils 124, 126 to the inner surfaces of therespective lumens 134, 138. That is, the slots 140, 142 make it easierto weld the filars 128, 130 inside the lumens 134, 138 from a positionoutside of the ring 122 by providing physical and visual access throughthe slots 140, 142 to those filars 128, 130 disposed inside the lumens134, 138. In the embodiment as best shown in FIG. 4B, each of the twofemale members 132, 136 can have two slots, with the first member 132having two slots 140A, 140B and the second member 136 having two slots142A, 142B (not visible in the figure). Alternatively, each member 132,136 may have only one slot or no slot.

The coiled conductor 150 according the embodiment depicted in FIGS. 5Aand 5B has a joint ring 152 having two male members 162, 166. The end ofthe first coiled conductor 154 is disposed over the first male member162, and the end of the second coiled conductor 156 is disposed over thesecond male member 166. In addition, in this implementation, theopenings of the lumens 164, 168 both have lips 172, 174 that can guideany elongated device being inserted through the ring 152 in eitherdirection without impeding the progress of the device.

In accordance with one embodiment, the ring 152 has an outer shoulder170 disposed on the outer surface of the ring 152 between the two malemembers 162, 166. The shoulder 170 can serve to separate the firstmember 162 from the second member 166 and has an outer diameter that canbe configured to fit within the lumen of the lead in which the coil 150is to be positioned. In addition, according to certain embodiments, theshoulder 170 can help to position the first and second coiled conductors154, 156 to ensure that the appropriate amount of each conductor 154,156 is positioned on each member 162, 166 to achieve an appropriatemechanical and/or electrical connection with the ring 152.

In alternative embodiments, other forms of coupling components can beused to couple two or more coiled segments in series. For example, thetwo or more coiled segments can be coupled together by any one ofseveral welding processes. FIG. 6 depicts a specific example of a coiledconductor 180 having a joint member 182 that is a weld zone 182. Thatis, the first coiled conductor 184 and the second coiled conductor 186are welded together at their respective ends to create a single coiledconductor 180 having a weld zone. “Weld zone” is intended for purposesof this application to mean any coupling component that is createdbetween two coiled conductors or coiled conductor segments based on awelding process without any separate mechanical coupling device orcomponent.

A weld zone such as the zone 182 in FIG. 6 can be created using severaldifferent methods, such as those depicted in FIGS. 7A, 7B, and 7C.

FIG. 7A depicts a method of creating a weld zone according to oneimplementation in which two weld bands are created at the ends of thecoil segments and then welded together. In this implementation, the twoweld bands 190, 192 are first created by welding together the filars atone end of each of the first coiled conductor 184 and the second coiledconductor 186. Once the weld bands 190, 192 are formed on the end ofeach conductor 184, 186, the two bands are then welded together to formthe weld zone 182. In one embodiment, the two bands 190, 192 are weldedtogether using a seam weld 194. Alternatively, any method of welding thetwo bands 190, 192 together can be used.

FIG. 7B depicts another method of creating the weld zone 182 couplingthe two conductors 184, 186, according to another embodiment. In thisembodiment, the filars 196 of the first conductor 184 are firstintertwined with the filars 198 of the second conductor 186, such thatthe filars 196, 198 are combined together in series in a repeatingfashion as shown in the figure. Once the filars 196, 198 areintertwined, the weld zone 182 is then created by welding theintertwined filars 196, 198 together.

FIG. 7C depicts yet another method of creating the weld zone 182coupling the two conductors 184, 186, according to a furtherimplementation. In this embodiment, the filars of one conductor areoverlapped with the filars of the other conductor. In the example shownin FIG. 7C, the filars 198 at one end of the second coiled conductor 186are overlapped with and disposed within the filars 196 at one end of thefirst coiled conductor 184. Alternatively, the filars 196 of the firstcoiled conductor 184 can be overlapped with and disposed within thefilars 198 of the second coiled conductor 186. Once they are overlapped,the filars 196, 198 can be welded together to create the welded zone182. It is understood that in some embodiments such as that shown inFIG. 7C, one coiled conductor may have a larger I.D. and O.D. than theother (such as, for example, the first conductor 184 having a largerI.D. and O.D. than the second 186 in the figure), thereby resulting ineasy insertion of one set of filars into the other. On the other hand,it is not a requirement that the coiled conductors having differentI.D.s and O.D.s.

Combining different conductor coils or conductor coil segments in seriesusing a coupling component such as any of the various embodimentsdescribed herein (including the various joint rings and welding zones asdescribed above) allows for creating or having a coil conductor that canexhibit widely different characteristics based on the different portionsor sections along the length of the conductor. That is, a conductor coilcan be constructed with two or more sections having differentcharacteristics that provide for optimal functional performance needs ofthe conductor.

In one example, it may be desirable that one or more sections of aconductor coil are coated while one or more other sections are not.Returning to FIG. 2A, the individual filars 86 of the proximal conductor82 are coated with an insulation coating 88. In one embodiment, thecoating is ETFE. Alternatively, the coating 88 can be silicone,polyurethane, PTFE, PET, FEP, or any other polymeric material that canbe used as a filar coating, whether insulative or non-insulative. In afurther alternative, the coating 88 can be any known material that canbe used in a coiled conductor coating. In the various embodimentsdiscussed herein, it is possible to have one or more coiled segments(such as segment 82 in FIG. 2A) along a coiled conductor while one ormore other coiled segments are uncoated (such as segment 84 in FIG. 2A).

Other characteristics can also be varied by coil segment. For example,it may be desirable that one or more sections have filars that havelarger outer diameters than the filars of one or more other sections ofthe same coiled conductor. As one example, the filars 86 of the proximalsegment 82 of FIG. 2A are thicker than the filars 92 of the distalsegment 84 as a result of the coating 88. Alternatively, uncoated filarsof one segment can simply be thicker than uncoated filars of anothersegment.

In a further embodiment, it may desirable that one or more sections havefilars having a different pitch than one or more other sections. Forexample, the filars 86 of the proximal segment 82 of FIG. 2A have adifferent pitch than the filars 92 of the distal segment as a result ofthe greater thickness of the filars 86. Alternatively, filars of onesegment can simply have a different pitch than filars of another segmentunrelated to any thickness differences.

In yet another embodiment, it may be desirable that one or more sectionshave filars made of a different material than one or more othersections. For example, in certain embodiments, the filars 86 of theproximal segment 82 of FIG. 2A could be made of a material that is moreflexible than the material of the filars 92 of the distal segment 84.Alternatively, any material that is known to be used in coiledconductors could be used in any one or more coiled segments, and one ormore other coiled segments could be made of any other of such materials,thus resulting in at least two segments having filars made of differentmaterials. In a further alternative, the two or more segments can bemade of the same material.

In further alternative implementations, it may be desirable that one ormore sections have a particular number of filars that is different fromone or more other sections. For example, in certain embodiments, theproximal coil 82 of FIG. 2A has four filars 86 while the distal coil 84has five filars 92. Alternatively, the number of filars can differbetween coiled segments or coiled conductors connected in series by anynumber of filars that are known to be used in a conductor coil.

Various other embodiments of conductor coils having two or more segmentswith different characteristics can be created using unique manufacturingmethods. For example, according to one implementation, the conductorcoil 220 depicted in FIG. 8 can be manufactured using a process thatresults in the coil 220 having a proximal segment 222 having five filarsthat each have an insulation coating and a distal segment 224 havingfive filars that are uncoated. Because they are not coated, the filarsof the distal segment 224 have a smaller outer diameter than the filarsof the proximal segment 222, thereby causing the distal coiled segment224 to have a smaller inner diameter and a smaller outer diameter thanthe coiled proximal segment 222.

The method, according to one implementation, begins by using a standardwinding process to wind five coated filars into a coiled segment thatwill be the proximal coiled segment 222. In one embodiment, the fivefilars are formed into a coil using a mandrel having a first outerdiameter that creates a coil having the desired inner diameter. When thewinding process has created a proximal segment 222 of the predeterminedlength, a coating removal process is started to remove the coating fromthe filars. In one embodiment, the coating removal process is a laserablation process using a laser such as an Excimer or CO₂ laser.Alternatively, any known coating removal process could be used. As shownin FIG. 8, the coating removal process results in a transition point 226along the coil 220 at which the coated proximal section 222 ends and theuncoated distal section 224 begins. The combination winding and coatingremoval process continues until the end of the distal segment 224 ofpredetermined length is reached.

In accordance with one embodiment, the O.D. of the mandrel changes atthe transition point 226 to a smaller O.D. In one implementation, thisis because the five filars being wound to create the distal coil have asmaller thickness as a result of the removal of the coating, and thus asmaller O.D. is necessary in order to ensure that the five filars arewound tightly without any space between the filars.

Alternatively, any second O.D. could be used. That is, the process couldinclude using a mandrel having a second O.D. that is smaller than thefirst to produce a distal coil with a smaller O.D. as described above,or the second O.D. could be larger than the first O.D. to produce adistal coil with a larger O.D. if that is desirable. In a furtheralternative, the distal coil could be wound with an O.D. that is thesame as the O.D. of the proximal coil. In yet other alternatives, amandrel having a third O.D. can be used to create a third segment of adifferent O.D., or a mandrel having additional segments havingadditional O.D.s could be used in any number to create any number ofadditional coiled segments.

It is understood that the above method could be performed in reverse.That is, the winding of the first segment could include a coatingremoval process to produce an uncoated segment, and then at thetransition point, the coating removal process could be stopped and thesecond segment could be produced with a coating. It is furtherunderstood that any process similar to those described herein could berepeated several times to produce coils of not only two segments, butalso three, four, or any number of segments having differentcharacteristics.

In a further alternative, the coating removal process is performed priorto the winding process. That is, the coating is removed from each of thefilars that are to be used in the coil prior to forming the filars intothe coiled configuration. In some embodiments, the amount of coatingthat must be removed in order to create the uncoated segment of thepredetermined length is calculated, and then that amount of coating isremoved. In another embodiment, the filar is first cut to thepredetermined appropriate length to create the coiled conductor of thedesired length. It is understood that in embodiments in which there ismore than one uncoated segment, the coating removal process is repeatedfor each of those segments.

In another alternative implementation, the coating removal process isperformed after the winding process. That is, the coiled conductor isfully wound using a coated filar or two or more coated filars, and thenthe uncoated segment or segments are created by performing the coatingremoval process on the fully wound coil.

As discussed above with the coupling component embodiments, it can bedesirable to have coiled segments with different numbers of filars.According to certain embodiments, the methods for manufacturing aconductor coil having two or more segments can also include methods forforming segments with different numbers of filars. More specifically,the methods disclosed herein include steps for winding a number offilars to form a coiled segment of a predetermined length and theneither cutting one or more of those filars and continuing to wind suchthat the second segment has fewer filars, or adding one or more filarsand continuing to wind such that the second segment has one or moreadditional filars.

In one embodiment in which the number of filars is reduced from thefirst segment to the second segment, the method includes starting with apredetermined number of filars that are wound into a coiled segmentusing a standard winding process with a mandrel. For purposes of thisexample, the predetermined number of filars is five, but it isunderstood that the first segment can have any known number of filars.When the winding process has created a first segment of thepredetermined length, one of the filars is cut. In one embodiment, theend of the cut filar is then welded or otherwise attached by any knownprocess to an adjacent filar. Alternatively, the cut filar is notattached. In a further alternative, two or more filars are cut.Regardless, the cutting of the filar results in a transition point alongthe coil at which the five filar segment ends and the four filar segmentbegins. The winding process then continues with four filars until thepredetermined end of the second (four filar) segment. It is understoodthat at this point the winding process may be complete (in embodimentsin which the coiled conductor has two segments) or it may continue withthe addition or removal of one or more filars and the winding of a thirdsegment, and perhaps subsequently the winding of additional segments aswell.

It is understood that other parameters beyond the number of filars maybe adjusted at the transition point as well. For example, if the numberof filars is reduced at the transition point, the resulting secondsegment will have to have a smaller I.D. and O.D. if the individualloops of the coil contact each other with no spacing between eachadjacent loop). As such, in one embodiment, the mandrel will have atransition point at the coil transition point at which the O.D. of themandrel will decrease accordingly to produce a coiled configuration withthe desired new O.D. and I.D.

In an alternative embodiment, the number of filars is increased betweenthe winding of the first segment and the winding of the second segment.In this embodiment, the method includes starting with a predeterminednumber of filars that are wound into a coiled segment using a standardwinding process with the mandrel having a predetermined O.D. Forpurposes of this example, the predetermined number of filars is four,but it is understood that the first segment can have any known number offilars. When the winding process has created a first segment of thepredetermined length, an additional filar is added by inserting anotherwire into the winding process. In one embodiment, the additional wire iswelded to an adjacent filar prior to beginning the winding of the secondsegment. Alternatively, the added filar is not attached. In a furtheralternative, two or more filars could be added. Regardless, the addingof the fifth filar results in a transition point along the coil at whichthe four filar segment ends and the five filar segment begins. Thewinding process then continues with five filars until the predeterminedend of the second (five filar) segment. It is understood that at thispoint the winding process may be complete (in embodiments in which thecoiled conductor has two segments) or it may continue with the additionor removal of one or more filars and the winding of a third segment, andperhaps subsequently the winding of additional segments as well.

As explained above, other parameters beyond the number of filars may beadjusted at the transition point as well. For example, in processes inwhich the number of filars is increased at the transition point asdescribed in the previous paragraph and the first segment had no spacebetween the individual loops of the coil, the resulting second segmentwill have to have a larger I.D. and O.D. as a result of the addition ofone or more filars. As such, in one embodiment, the O.D. of the mandrelchanges at the transition point to a larger O.D. that will produce acoiled configuration with the desired new O.D. and I.D.

The ability to manufacture or use coiled conductors having two or moresegments with differing characteristics provides greater flexibility inthe design of implantable medical leads. That is, a segmented coiledconductor allows for optimization of target lead characteristics andfunctional performance, such as set forth in the exemplary lead depictedin FIG. 9 and discussed below. Certain medical lead requirements canmake it desirable for the lead to have different characteristics indifferent segments along the length of the lead. As such, a coiledconductor that has different segments with different characteristicsalong the length of the conductor can be used to optimize suchrequirements.

In one example of a lead with design requirements that can be optimizedusing a coiled conductor having two or more segments, the lead 240depicted in FIG. 9 has two segments 242, 244 along its length for whichdifferent characteristics are required, and a transition point 246between those segments. In this exemplary lead 240, the proximal segment242 has a polyurethane body (which has relatively high stiffness incomparison to lead bodies made of other materials), must often meetintracardiac and subcutaneous flexural fatigue requirements, and mustoften be configured to receive finishing wires and guide wires. As such,it is desirable to have a coiled conductor with a proximal segment thathas an I.D. large enough to receive any finishing or guide wires, aminimized pitch and filar count to optimize its flexural fatiguecharacteristics, and a material or coating that prevents metal ionoxidation of the polyurethane body tubing.

In contrast, the distal segment 244 of this lead has a silicone body andmust be capable of being formed into a bias shape such as the spiraledshape 248 as shown in the figure that meets the bias fixationrequirements for the distal end and have a minimized diameter to producethe smaller tip geometry necessary for the lead. On the other hand, thedistal segment 244 need only meet the intracardiac flexural fatiguerequirements and need only be configured to receive guide wires. Assuch, the distal segment of the coiled conductor, in comparison to theproximal segment, should have a smaller O.D., an increased pitch andfilar count to enhance the ability of the coil to be formed into thedesired bias shape, and does not need to be configured to prevent metalion oxidation (since silicone is not susceptible to it).

Given the flexibility provided by the various coiled conductorembodiments and manufacturing methods disclosed herein, a coiledconductor can be manufactured that can satisfy the requirements setforth above to optimize the desired lead characteristics. Similarly, itis understood that the flexibility of the variable coiled segmentsaccording to the various embodiments disclosed herein allows foroptimization of many different lead requirements.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

We claim:
 1. A method of constructing a coil conductor of an implantablemedical lead, the coil conductor having at least a proximal segment anda distal segment, the method comprising: winding at least one filarsinto a coiled configuration over a first section of a mandrel to formthe proximal segment, wherein the proximal segment comprises a firstouter diameter and a first pitch, the proximal segment ending at atransition point, the at least one filars having a coating thereonduring the winding of the proximal segment; removing the coating from asection of the at least one filars; and winding the section of the atleast one filars from the transition point into a coiled configurationover a second section of the mandrel to form the distal segment, thedistal segment comprising a second outer diameter and a second pitch,the distal segment wound from the section such that the at least onefilars are uncoated along the distal segment and are coated along theproximal segment.
 2. The method of claim 1, wherein removing the coatingcomprises removing the coating with a laser.
 3. The method of claim 1,wherein removing the coating from the section of the at least one filarscomprises removing the coating after the proximal segment has beenwound.
 4. The method of claim 3, wherein and the coating is removed fromthe section of the at least one filars while the distal segment is beingwound.
 5. The method of claim 3, wherein the coating is removed from thesection of the at least one filars after the distal segment is wound. 6.The method of claim 3, wherein the coating is removed from the sectionof the at least one filars before the distal segment is wound.
 7. Themethod of claim 1, wherein the second outer diameter is less than thefirst outer diameter.
 8. The method of claim 1, wherein the first pitchis less than the second pitch.
 9. The method of claim 9, wherein theproximal segment has different flexural characteristics than the distalsegment based at least in part on the first pitch being less than thesecond pitch.
 10. The method of claim 1, wherein: winding the proximalsegment comprises winding the proximal segment with a plurality offilars, including the at least one filars, and the method furthercomprises removing at least one of the plurality of filars after windingthe proximal segment but before winding the distal segment such that theproximal segment comprises more filars than the distal segment.
 11. Themethod of claim 1, further comprising adding at least one more filar tothe at least one filars after winding the proximal segment but beforewinding the distal segment such that the distal segment comprises morefilars than the proximal segment.
 12. A method of constructing a coilconductor of an implantable medical lead, the coil conductor having atleast a proximal segment and a distal segment, the method comprising:winding a first number of at least one filars into a coiledconfiguration over a first section of a mandrel to form the proximalsegment, wherein the first section comprises a first outer diameter, anda first pitch, the proximal segment ending at a transition point and acoating disposed on the at least one filars such at the at least onefilars have a coated configuration while the proximal segment is wound;removing the coating from a section of the at least one filars; andwinding a second number of the at least one filars from the transitionpoint into a coiled configuration over a second section of the mandrelto form the distal segment, the second section comprising a second outerdiameter, and a second pitch, the first pitch and the first innerdiameter are different from the second pitch and the second outerdiameter, wherein the coating is removed from the at least one filarsafter the winding of the proximal segment along a section of the atleast one filars that will form the distal segment such that the atleast one filars is coated along the proximal segment and uncoated alongthe distal segment.
 13. The method of claim 12, further comprisingremoving one of the first number of filars at the transition pointbefore winding the second number of filars, whereby the second number offilars is less than the first number of filars.
 14. The method of claim12, further comprising adding a filar at the transition point beforewinding the second number of filars, whereby the second number of filarsis greater than the first number of filars.
 15. The method of claim 12,wherein the second outer diameter of the mandrel is smaller than thefirst outer diameter of the mandrel.
 16. The method of claim 12, furthercomprising winding a third number of the at least one filars beginningat a second transition point into a coiled configuration over a thirdsection of the mandrel to form a third segment, wherein the thirdsection comprises a third outer diameter and the third segment comprisesthe third number of at least one filars, a third pitch, and a thirdinner diameter, wherein at least one of the second number of filars, thesecond pitch, the second inner diameter, and the second outer diameteris different from at least one of the third number of filars, the thirdpitch, the third inner diameter, and the third outer diameter.
 17. Amethod of constructing a coil conductor of an implantable medical lead,the coil conductor having at least a proximal segment and a distalsegment, the method comprising: winding at least one filars into acoiled configuration over a first section of a mandrel to form theproximal segment, wherein the proximal segment comprises a first outerdiameter and a first pitch, the proximal segment ending at a transitionpoint, the at least one filars having a coating thereon during thewinding of the proximal segment; and winding the section of the at leastone filars from the transition point into a coiled configuration over asecond section of the mandrel to form the distal segment, the distalsegment comprising a second outer diameter and a second pitch, thesecond outer diameter is less than the first outer diameter, the firstpitch is less than the second pitch.
 18. The method of claim 17, furthercomprising removing the coating from a section of the at least onefilars after the winding of the proximal segment, wherein the distalsegment is wound from the section such that the at least one filars areuncoated along the distal segment and are coated along the proximalsegment.
 19. The method of claim 18, wherein removing the coatingcomprises removing the coating with a laser.
 20. The method of claim 17,wherein: winding the proximal segment comprises winding the proximalsegment with a plurality of filars, including the at least one filars,and the method further comprises removing at least one of the pluralityof filars after winding the proximal segment but before winding thedistal segment such that the proximal segment comprises more filars thanthe distal segment